The act of adding another tire to both sides of the rear axle of any car (making it a dually). While this might not increase the towing capacity of most cars, it sure looks fucking cool. Also called "trailer-parking" or "white-trashing."

Cletus: "Hey, Brandine, we gotta move."
Brandine: " The only car we got is the IROC, how we 'sposed ta move the trailer."
Earl: "Hey, Cletus, ya outta put that Camaro a dually, y'all could sure trail that home 'a yours mighty far if that IROC were a dually!"